A.T. Robertson Commentary Luke 18:38

"And he cried, saying, Jesus, thou son of David, have mercy on me." — Luke 18:38 (ASV)

He cried (εβοησεν). Old verb, βοαω, to shout, as in 9:38.

Son of David (υιε Δαυειδ). Shows that he recognizes Jesus as the Messiah.